Boat hull having an upwardly arched bottom



Feb. 21, 1956 E. w. cox 2,735,392

BOAT HULL HAVING AN UPWARDLY ARCHED BOTTOM Filed DEC. 10, 1952 2Sheets-Sheet l I I 'l I I N I I y ya JNVENTOR.

Earl W. Cox I Flg I Feb. 21, 1956 w, cox 2,735,392

BOAT HULL HAVING AN UPWARDLY ARCHED BOTTOM Filed Dec. 10, 1952 2Sheets-Sheet 2 JNVENTOR. E0 rI W. Cox

477'OZNEYJ rearward flow in the BOAT HULL HAVING AN UPWARDLY ARCHEDBOTTOM Earl W. Cox, Seattle, Wash. Application December 10, 1952, SerialNo. 325,051

3 Claims. (Cl. 11462) This invention relates to improvements in boatsand has reference more particularly to improvements in the details ofconstruction of the hulls of propeller driven boats. More specificallystated, the present invention pertains, first, to the design or shape ofthe water engaging surfaces of a boats hull, and to the shape andrelationship to each other of its water displacing portions.

It is one of the principal objects of this invention to provide a boathull embodying novel features of design whereby water resistance totravel is reduced and faster speed made possible with the same or even areduced power input.

It is a further object of the invention to provide a boat hull that ischaracterized by the provision in its bottom and substantially to itsfull length of a longitudinal, downwardly facing semi-cylindricalchannel of substantial depth, into which water that in the operation ofthe common type of boat would be shoved forwardly, downwardly orlaterally by the bottom and bow in the forward travel of the boat, willof the propeller or propellers and moved through the channel to thestern of the boat, and there forcibly discharged rearwardly withjet-like propelling effect, to fill in the cavity that otherwise wouldbe formed incident to the forward travel of the boat. Thus, by thisdesign, I eliminate both the usual retarding pressure of displacementwater against the bow of the forwardly moving boat and the speedreducing drag of cavitation and after-tow.

It is a further object of the present invention to so shape the sidesand bottom of the longitudinal channel as provided in the bottom of thehull, and to so dispose a keel and the driving propeller or propellersin the channel that the latter will move water from the forward end ofthe boat therein sternward in two parallel streams and will discharge itwith jet-like propelling effect, and in the sucking of water into thechannel at its forward end will tend to create a cavity in the keeldivided channel, forwardly of the propellers, into which the waterswhich are normally divided and outwardly displaced by the bow willconverge and thus the usual retarding effect of Water headed into by theboats prow will be eliminated.

Still another object of my invention is to provide a hull constructionfor boats that is characterized by those features of construction aboverecited and wherein the channel as formed in the bottom of the hull iscentrally and longitudinally divided by a keel that extends from the bowend to a substantial distance rearward thereof, and in which keel, apropeller shaft and drive gear housing is incorporated as a part of oran extension of the keel; this housing being of such nature as tosomewhat constrict with vcnturi effect the two ducts into which thechannel is divided by the keel so that the action of propellers, locatedin keel openings forwardly and rearwardly of this gear housing, willresult in accelerated flow of water in the ducts at the places ofrestriction and a forced ducts that is of greater speed than be drawn bythe action ttes atent 2,735,392 Patented Feb. 21, 1956 the relativerearward travel of water along the sides of the hull, so that after-towand the folding in of the water around the stern will be avoided.

Yet another object of the invention is to so design the opposite sidesof the present hull that the water along the outside thereof ispractically undisturbed by the forward travel of the hull and isrestrained from rushing from along the sides of the boat into thelongitudinal channel or duets with retarding effect on the rearwardlypropelled streams of water in the channel.

It is a further object of my invention to provide a boat hull ofspecific and novel design, featuring the provision in its bottom of alongitudinal channel that is centrally and longitudinally divided for atleast a part of its length by a keel, a portion of which keelincorporates means therein for transmitting power to the propeller orpropellers and also provides a low center of gravity that gives greaterstability and adds sea worthiness to the boat.

In accomplishing these and other objects of the invention, l haveprovided the improved details of construction, the preferred forms ofwhich are illustrated in the accompanying drawings, wherein- Fig. 1 is aside view of the hull of a boat embodying the improvements of thepresent invention therein; parts thereof being broken away for betterunderstanding.

Fig. 2 is a bottom view of the hull, showing the central channel andextent of the keel dividing the channel in two parallel passages; alsoshowing the propeller locations.

Fig. 3 is an elevation of the hull, as seen from directly forward of theprow.

Fig. 4 is an elevation of the hull, as seen from directly rearward ofthe stern.

Fig. 5 is a partial plan view substantlialy at deck level, of structuralmembers in the hull construction, and showing the location of rudders.

Figs. 6, 7 and 8 are cross-sectional views taken on lines 66, 7-7 and88, respectively, in Fig. 2.

Referring more in detail to the drawings- First describing the novelfeatures of design and the particular shaping of the water contactingsurfaces of the present hull:

The hull, which is designated in its entirety by reference numeral 10,is shown more particularly in Figs. 1 and 2, to be conventional in itsgeneral outline and plan, and in so far as its structure from the waterline downwardiy is concerned, it has vertical and parallel opposite sidewalls 11-11 extending substantially to its full length. The chine lines12, where the side walls Ill-11 join with the bottom, 13, are straightfrom end to end and are uniform in depth below the water line. waterline is designated in the various cross-sectional views by line W-W.

downwardly and rearwardly rounded edges designated at S in Figs. 1 and2. Likewise, it is to be observed that the main portion of the sternstructure of the hull is above the water line and extends rearwardly ofthe sides 11 of the hull which are shown to terminate in the ruddermounts 'S'.

in the various cross-sectional views, the hull bottom 13 is shown to beupwardly transversely arched in substantially a semi-cylindricallycurved form, thus forming the hull, from stem to stern, with alongitudinal, downwardly facing channel. This channel extendssubstantially to the full width of the hull as defined by the oppositeside walls 11-11, and the top of the arch extends along the centrallongitudinal plane of the hull at a level just slightly below thehorizontal plane of the water line.

It will be understood by reference to the several crosssectional viewsthat, in effect, the hull comprises two laterally spaced andlongitudinally extending hull sections 11a and 11b which are so designedas to elfect sufficient displacement of water that the hull will becaused to float at the desired level. The upwardly arched inside wallsof these two hull sections together define the inverted centrallongitudinal channel of the hull and the vertical side walls thereofoperate to hold back outside Waters, that are other than displacedwaters, from the channel and propellers. Thus, the positioning ofpropellers in the channel as presently explained is of great importanceespeciallyin respect to the forward propeller, which has the duty ofproducing cavitation to accommo date the oncoming bows water and reduceresistance to forward travel resisting. The greater the cavitation orsuction produced, the less will be the bow resisting pressure.

The present invention further provides that the longitudinal channelformed by the transversely arched bottom is longitudinally divided atleast for a portion of its length, by a keel 18. The keel is shown inFigs. 1 and 2, to extend rearwardly from the point of the bow to abouttwo thirds the length of the hull. However, in some instances it mightbe extended to the stern end if found necessary or desirable to meetvarious requirements.

The keel extends to a depth slightly below the level of the chine linesof the opposite side sections 11:: and 11b and at its forward end itsedge is gradually curved upwardly to the prow, as at k in Fig. 1. It isanticipated that in some boats, using a single propeller, locatedamidships, the keel would terminate at the location of the propeller.Furthermore, in some boats, especially those of small size, such asthose boats using out-board motors or similar means for propulsion, acentral keel would not be required and could be omitted.

It is herein illustrated that the keel 18 divides the longitudinalchannel into two co-extensive, parallel passages or ducts which in theelevational and cross-sectional views are designated at p and p. Theseducts extend from the bow to the rear end of the keel where they merge.At its forward end, the channel as formed by the arched bottom, hasoutwardly flared entrance valleys or mouths into which water fromimmediately forwardly of the bow ends of hull and side sections,referred to herein as head water is sucked by the propeller action asdistinguished from the usual forward, lateral and downward forcing ofthis water by the forwardly traveling boat.

To provide these flared entrances to the channel, the curved top wall isgradually upwardly and outwardly formed to define a sort of valleyleading into each side of the channel. The valleys are designated at Vand V in Figs. 2 and 3, and they serve, in the forward travel of thebull in the water, to accelerate movement of displacement or head watersinto the channel and toward the propellers.

The action of the propellers in forward of the bow ends of the boat intothe dual passages or ducts and discharging it rearwardly tends to createa cavity immediately forward of the bows and to move the displaced waterrearwardly through the channel to the rear of the forward propeller anddischarge it to the stern end thus to eliminate cavitation at the sternand prevent any retarding after-tow. If a single propeller should beused, it would be so located and operated as to perform the functions ofthe two propellers, as herein illustrated.

in Fig. 2 of the present used to indicate direction of ter from theducts under influence is indicated that the water is drawn into theforward ends of the dual passages p and p from forwardly and laterallyof the bows point and that it is discharged from the sucking the waterfrom drawings, arrows have been inflow and discharge of waof thepropellers. It

rear end of the bottom channel and diverges laterally. The straight,upright outer side walls of the hull have no tendency as the boat movesforwardly to cause any outward or lateral movement of water at theoutside thereof and they serve to prevent the water at the sides of thehull entering the passages. For this reason the propellers are notaffected by and do not have to move a any Water except that contained inthe passages and received from the forward end of the hull.

The location of propellers is dependent somewhat on boat requirements.In the present instance, I have illustrated the hull asequipped with twopropellers 25 and 26 which respectively, are located in the plane ofkeel 18 about one-third and two-thirds of the distance from stem tostern. The forward propeller 25 is disposed within a recess 25R in thekeel and extends equally into each duct 2 and p, while the rearwardpropeller 26 is located immediately beyond the terminating edge of thekeel or housing 18x which is a component thereof and which will now bedescribed.

Formed as a component part of or in combination with the keel, as arearward extension of the forwardly located keel 18, is a housing whichis designated by reference character 18x and which is that portion ofthe keel located between the propellers 25 and 26. The spaced, oppositeside walls of this housing converge forwardly to merge gradually intothe relatively narrow keel as shown best in Fig. '2. Likewise theyconverge rearwardly to a feather edge just forwardly of the propeller26. Also, these walls converge downwardly to a thin edge that coincideswith the bottom longitudinal edge of the keel.

Contained in the housing 18x, which will hereinafter be referred to as apontoon or swell, lengthwise thereof are the propellermounting anddriving shafts 25s and 26s which, respectively, mount the propellers 25and 26 thereon. These shafts are equipped with sprocket wheels overwhich driving chain belts 2'7 and 28 operate to drive the shafts; thesebelts being driven by engines designated in Fig. l at 29 and 30.

' The embodiment of the swell 13x in or with the keel 18 causes the twopassages p and p, as separated thereby to be somewhat constricted at thelocation of the section line 7-7, and thus the propellers coact moreeffectively to discharge the incoming water rearwardly with jet-likepropelling action. The rearward end of the channel is fantailed into thehull to give a flared effect that results in the easy rearward andlateral discharge of the streams of water from the passages.

The propeller shafts, their supporting bearings, and propellers addweight at a particular location that results in a low center of gravitythat gives stability and better balance to the boat.

With the hull constructed in this manner, it can be understood that thesides of the hull cut through the water, retaining that at the outsideof the hull from the longitudinal channel. Only that water that entersthe channel at its forward end must be moved by the propellers and thechannel passages are so shaped that, under the influence of thepropellers, especially the forward one, there is a tendency to produce acavity forward of the bow into which the boat advances without headwater resistance. The propellers, being located in the ducts at pointswhere the pressure of rearwardly flowing water accumulates, will operatewith greatest efficiency in effecting the jet-like propulsion of thewater from the rear end of the channel to drive the boat forward and toovercome cavitation and after-tow.

Since the water pressures as sustained by the present hull aresubstantially reversed from those as applied to normal construction, adifferent frame structure than ordinarily used is desirable. Strongbulkheads are neees sary, especially on how ends, to give the necessarya strength.

A pattern of the preferred constfuction is shown in Figs.

5 to 8; Fig. 5 being a horizontal section taken just below deck level,that is, at about the water line.

In Fig. 5, longitudinal plates 40 and 41, disposed horizontally and invertical spacing, are shown to be extended between the side walls 11 andthe upwardly arched bottom 13, and these provide water tightcornpartments between them that extend to substantially the full lengthof the hull.

Across the top of the arch as formed by the bottom plate 13, aretransversely directed plates 45, best seen in Fig. 5; these beingdisposed vertically on edge and welded to the bottom and also to thoseportions of the plates 41 with which their opposite end portionsoverlap. The end edges of the cross-plates 45 are welded tolongitudinals 4848 which are disposed vertically on edge and equallyinwardly spaced from the opposite side walls 11. Division plates 49 areextended between the longitudinals and adjacent sidewalls 11. Also,other division plates 50 located between the plates 40 and 41 areextended between the arched bottom 13 and the side walls. The divisionplates 49 are staggered relative to the spacing of plates 50 as will beunderstood by reference to the showing of these parts in Fig. 5.

The main deck of the boat is designated at 55 in Figs. 6, 7 and 8 and itis supported by the longitudinals 48 and cross plates 45 and is weldedto the side walls 11-11 It is shown in the several views that, above thedeck 55, the side walls of the hull are outwardly curved, and betweenthese walls and upper structure, suitable bracing is provided.

The particular arrangement of longitudinals and cross beams and divisionplates as shown in Figs. 5 and 8, properly welded together gives allstrength required and solves the various problems of shrinkage, strainsand contortions with which builders of such craft are quite familiar.

The various compartments provided can be used for storage space, forfuel, water, cargo, etc.

In Fig. 5, I have shown rudders 60-60 arranged at sides beyond but inalignment with the side walls. However, the location of rudders andnumber used would depend somewhat upon type or size of boat. It might insome cases be more practical to employ a single rudder, located inalignment with the keel.

The feature whereby the present invention is characterized, broadlystated, is the collecting of the displacement waters by the bows andforcing them centerwise beneath the bottom, and locating a propeller atthe point where the peak of pressure of the displacement watersaccumulates according to speed; the propeller operating to force thedisplacement sternward, leaving a cavity for oncoming bows waters andpressures to fall into. The displacement, then under propeller pressure,pressing against waters at the stem with elimination of the after-drag.

Having thus described my invention, what I claim as new therein, anddesire to secure by Letters Patent, is:

l. A boat having a hull formed with a water dividing prow and withopposite sidewall portions extending substantially to the full length ofthe hull in parallel vertical planes and to equal, uniform depth, andsaid hull having a bottom of upwardly arched and substantiallysemi-cylindrical form, extended between and joined with said sidewallportions along their lower edges and providing a water confining channelthat opens to prow and stern ends of the boat, said bottom havingoutwardly and upwardly formed portions at its forward end, at oppositesides of the prow, joined with the forward ends of said sidewallportions to provide cut-waters and forming upwardly and laterally flaredvalleys whereby head waters are funneled into said channel, as the boatmoves forwardly and said bottom having similarly upwardly formedportions at its rear end, joined with the rear ends of said sidewallportions; said bottom and said sidewall portions as thus joinedproviding parallel, laterally spaced water displacement bows whereby thehull is floated in the water with the top of the arched bottomsubstantially at the level of the water line, and a boat drivingpropeller positioned in said channel in its central longitudinal planeand substantially above the level of the lower edges of said sidewallportions of the hull.

2. A boat as in claim 1 wherein a keel is formed centrally along theboat bottom, extending to the full depth of the sidewalls and dividingsaid channel into dual passages, and propellers set in the keel andoperable to effect the forced flow of channel waters in said dualpassages for propulsion of the boat.

3. A boat as in claim 2 wherein a keel is formed centrally along theboat bottom, extending substantially to the depth of said sidewallportions, and dividing said channel into dual passages; said keel beingprovided along one part thereof with a swell of passage constrictingformation, providing venturis through which the channel confined watersare caused to flow, under the propeller influence with increasedvelocity and discharged therethrough with jet action.

References Cited in the file of this patent UNITED STATES PATENTS923,123 Ishoy May 25, 1909 1,061,826 Didlake May 13, 1913 1,599,312Passy-De Chimang Sept. 7, 1926 1,886,471 Passy-De Chimang Nov. 8, 19322,356,349 Persson Aug. 22, 1944 2,366,590 Brownback Jan. 2, 1945 FOREIGNPATENTS 2,813 Great Britain July 24, 1877 341,059 France May 31, 1904408,278 Germany Jan. 12, 1925

